Part One: The QOS Realm

1 The QOS World

Quality of Service (QoS) has always been in a world of its own, but as the technology has been refined and has evolved in recent years, QOS usage has increased to the point where it is now considered a necessary part of network design and operation. As with most technologies, large-scale deployments have led to the technology becoming more mature, and QOS is no exception.

The current trend in the networking world is convergence, abandoning the concept of several separate physical networks in which each one carries specific types of traffic, moving towards a single, common physical network infrastructure. The major business driver associated with this trend is cost reduction: one network carrying traffic and delivering services that previously demanded several separate physical networks requires fewer resources to achieve the same goal.

One of the most striking examples is voice traffic, which was previously supported on circuit-switched networks and is now starting to be delivered on the “same common” packet-switched infrastructure.

The inherent drawback in having a common network is that the road is now the same for different traffic types, which poses the challenge of how to achieve a peaceful co-existence among them since they are all competing for the same network resources.

Allowing fair and even competition by having no traffic differentiation does not work because different types of traffic have different requirements, just like ...

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